Writing in his autobiography Spare — via the Independent — Harry says he wanted to go to the apocalypse-themed party with Markle, but also maintain his anonymity as their relationship was not yet public.
Harry wrote: “For help with my costume, I turned to a friend, the actor Tom Hardy, before I left home."
He then recounted his conversation with the actor: “I phoned him to ask if I could borrow his costume from Mad Max. ‘The whole thing?’ ‘Yes, please, mate! The whole kit!’”
The prince also said: “The party was loud, dark, drunk – ideal. Several people did double takes as Meg passed through the rooms, but no one looked twice at her dystopian date. I wished I could wear this disguise every day.”
The party was held at Toronto's branch of Soho House.
Harry met Hardy when he became an ambassador for The Prince's Trust in 2010, and the actor attended the Prince's wedding to Meghan Markle in 2018, posting a picture of the couple to his Instagram account on their wedding day.
Along with a photo of them smiling and waving, Hardy wrote the caption "Boss" along with a bunch of emojis. He also commented on his own post saying "Congratulations".
In an interview with Esquire in 2018, Hardy refused to discuss the wedding calling it 'deeply private' but said that Harry as 'a f***ing legend'.
The book, which is set to be one of the best selling of 2023, also features an account of Harry doing magic mushrooms at the house of Friends star Courteney Cox.
Describing his experience on magic mushrooms, Harry said: “Beside the toilet was a round silver bin, the kind with a foot pedal to open the lid. I stared at the bin. It stared back. Then it became… a head. I stepped on the pedal and the head opened its mouth. A huge open grin."
Watch below: Prince Harry's Spare becomes UK's 'fastest-selling' non-fiction book.